Another key member of the Federal Reserve is indicating to circle September on your calendar for an increase in interest rates. Low rates risk causing imbalances in the financial system, including a booming commercial real-estate market, which could undermine the expansion, said Ms. George, a prominent skeptic of the Fed's easy money policies who dissented at the central bank's July policy meeting when officials declined to raise rates. "It doesn't mean I think it needs to happen rapidly".

A Federal Reserve rate hike next month would provide a boost for the rest of the world and allow for a further hike this year, the co-founder of a Swiss investment advisory firm told CNBC on Thursday.

On Sunday, Fed Vice Chairman Stanley Fischer said the U.S. job market was close to full strength and still improving - comments viewed by some investors as underlining the case for a rate hike.

Second-quarter gross domestic product (GDP) data was below economists' expectations, but George believes that in the second half of 2016, US real GDP could grow by three percent.

"We're beginning to see wage growth in a way that suggests that the consumer is going to be in a good position to spend", George said. She said that a stronger second half could bring full-year GDP growth to two percent.

Kansas City Fed president Esther George, whose bank has hosted the conference here since 1978, had an even stronger message.

"In light of the continued solid performance of the labor market and our outlook for economic activity and inflation, I believe the case for an increase in the federal funds rate has strengthened in recent months", Yellen said.